The Pediatric Cardiomyopathy Registry (PCMR) has become a registering center for children with cardiomyopathy, one of the leading causes of morbidity and mortality in infants and children. We maintain the PCMR for children with different forms of cardiomyopathy in order to collect and organize relevant clinical and demographic information as an active and available resource for clinicians and scientists, allowing for increased awareness and knowledge of pediatric cardiomyopathy and its causes and the development of new diagnostic and therapeutic approaches. We are applying for continued funding of the PCMR to foster increased understanding of this devastating clinical problem that is not being addressed by any other study or organization. We will address important questions that have not yet been adequately studied. This study will draw on the strength of our current cohort of well characterized patients as a natural history study and also expand prospective data collection within restricted regions with complete capture of population- based cases. We propose 3 primary specific aims: l. To confirm whether the regional, ethnic group, time gender, age, and type of cardiomyopathy differences in the incidence of cardiomyopathy observed in the PCMR are correct by prospectively capturing two distinct regions of the United States; 2. To determine whether baseline factors at diagnosis or trends over time predict outcomes of mortality, late abnormalities of ventricular structure and function, congestive heart failure, listing for cardiac transplantation, Or receiving a cardiac transplantation; 3. To assess the functional status of children with cardiomyopathy. Our primary hypotheses are that: 1. During the period of the registry, the percentage of pediatric cardiomyopathy Cases that are diagnosed as idiopathic will decrease (i.e., etiologies will be found for a larger percentage of cases, and 2. At the time of diagnosis of cardiomyopathy, factors such as gender, ethnic group, age, type of cardiomyopathy, and presence or absence of a syndrome can help predict outcomes, such as the need for medical management, the need for surgical management (transplant), or the failure of both medical and surgical management (death).